Submitted by chrisdube on Sat, 07/30/2011 - 06:07
Posted in
Hi,
I'm new to this forum but I've been reading a lot of the great info on this site for a few months. I finally decided to get serious about designing and building a dolly. My goal is a low cost, relatively light weight dolly that I can take backpacking. I got a lot of inspiration from the dolly v1 prototype. Here is my design so far.
The rail is 80/20, and the slider is their linear bearing system. I am thinking of getting a shorter piece of rail for backpacking and a longer (72" or so) piece for more travel.
*15 Series 1.5" x 3.0" Lite Smooth T-Slot Aluminum Extrusion, Part # 1530
*15 Series Double Flange Linear Bearing, Part #6824
Here is my shopping list from SDP/SI:
The power transmission is with a 5mm HTD pitch, 9mm wide timing belt. The motor side has a 12-tooth pulley. The free end is just two flat aluminum pieces with bearings and a shaft. I am still working on a good way to attach the timing belt to the slider and add quick release capability.
My electronics are an Arduino, DFRobot LCD Shield and an EasyDriver. I am hoping to run miniE (right here!)
I am planning on using the Anaheim Automation 17Y-302S-LW4. Stepper motors still confuse me, but assuming the ideal torque of 61 oz-in, with the 12-tooth pulley (.75in pitch diameter) that works out to just over 10 lbs of pull. I am fine with even half of that, as right now I'm using an XSi and Sigma 10-20.
Any suggestions / problems that you guys can see? My main worry is the stepper not being powerful enough. I want to avoid using a geared motor if possible, but I may have to?
Thanks,
-Chris
I don't have any issues with
I don't have any issues with my ED. My 2 meter dolly can stand up vertically and the cart is moving without any issues.
I had the same worries when I built my dolly. It's easy to over size it all. But until now the ED worked out well, which is something I did not expect at all! I do have a Pololu driver at home. But I never got it to work. I think its broken out of the factory because I have 4 other drivers that do work. No Pololu for me in the near future.
Weren't you going to use the
Weren't you going to use the Anaheim Automation 23L9104XCS-02, which has 151 oz-in of torque?
Also, how did you get to the "10 lbs of pull" conclusion?
What most concerns me about the motors, is knowing if they are able to pull the camera if using the dolly in a "not horizontal", inclined position, forcing the motor to pull more weight...
Been busy with some other
Been busy with some other projects but I got back to getting the dolly working. On the electronics end of things, the LCD shield is running miniE which is working out great. I put a heatsink on the easydriver which got quite hot when moving a lot of weight. When horizontal, motor sleep helps with heat and power consumption. The driver and optoisolator are on a small piece of protobaord. I also wired an 8v regulator in which powers the Arduino nicely. It should also power the camera but I haven't tested that yet. I ordered a ProtoScrewShield to put between the Arduino and the LCD shield so I can break out the wires below it and mount the LCD and buttons flush with a project box.
pds wrote:Weren't you going to use the Anaheim Automation 23L9104XCS-02, which has 151 oz-in of torque? Also, how did you get to the "10 lbs of pull" conclusion? What most concerns me about the motors, is knowing if they are able to pull the camera if using the dolly in a "not horizontal", inclined position, forcing the motor to pull more weight...That is the motor I am using. I got it on ebay for $30 and it is incredible. 0.9 deg step angle and 8 microsteps means 3200 steps/rev. Not even turned up to full current, the easydriver will lift Canon XSi with battery grip and Sigma 10-20 vertically just fine at max speed. The max speed is pretty fast (about 1 ft every 3 seconds). I could of course get a bigger pulley on the motor end and speed that up if I have the need for faster motion for live video. I haven't accurately measured the holding torque, but I'd estimate it to be about 20 lbs.
schopaia wrote:Looks great! Just a couple of questions - did you machine the aluminum pieces yourself (for the pieces that are holding the gear in the photos)? And does the belt you selected fit in the undercarriage of the sliding platform? I was thinking of ordering a narrower belt... Yeah I did machine the brackets, if you could call it machining. Just used an angle grinder and a drill. I tapped threads in the bottom of the grooves in the 8020, but I realized right after all that work that I could have just used a bolt and nut which would sit in the groove (8020 sells special trinkets that do exactly this). The 5mm belt fits in the center of the extrusion with plenty of room. Although you could use a 3mm belt if you want - it would be plenty strong.
cronix wrote:I don't have any issues with my ED. My 2 meter dolly can stand up vertically heh...Viagra is a hell of a drug
A little video of it moving (slowly): http://www.youtube.com/watch?v=sMwf45HdiV0
Still to do
*Electronics packaging
*Redoing the motor end mount which is a bit of a hack job because I didn't have any aluminum angle big enough
*Redoing the belt holder - right now it is hard to use and interferes with the ballhead.
Just thought I would post a
Just thought I would post a few pictures of my setup and give thanks for the (most helpful) post. I used most of the parts you are using but substituted the sparkfun stepper motor.
Hi... Thanks for the great
Hi... Thanks for the great info. I was wondering if you could repost the SDP/SI shopping list... the image seems to be unreadable now? Odd...